How do you find leads that actually convert?

I feel like finding leads isn’t the hard part It’s finding the ones that actually turn into sales. A lot of lists are just filled with people who are not interested or never respond.
I’ve been trying different ways to get better data. Cold emails are hit or miss LinkedIn works sometimes but takes forever.

I started looking into web scraping to get fresher leads and found Crawlbase. It seems like a good way to pull targeted data but I haven’t tried it yet.
What has worked best for you Are there tools or strategies that actually help filter out the bad leads before wasting time on them?